Detailed Instructions: In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Problem:Question: Where else are Chemokine receptors found? Passage:Chemokine receptors are G protein-coupled receptors containing 7 transmembrane domains that are found predominantly on the surface of leukocytes, making it one of the rhodopsin-like receptors. Approximately 19 different chemokine receptors have been characterized to date, which share many common structural features; they are composed of about 350 amino acids that are divided into a short and acidic N-terminal end, seven helical transmembrane domains with three intracellular and three extracellular hydrophilic loops, and an intracellular C-terminus containing serine and threonine residues that act as phosphorylation sites during receptor regulation. The first two extracellular loops of chemokine receptors are linked together by disulfide bonding between two conserved cysteine residues. The N-terminal end of a chemokine receptor binds to chemokine(s) and is important for ligand specificity. G-proteins couple to the C-terminal end, which is important for receptor signaling following ligand binding. Although chemokine receptors share high amino acid identity in their primary sequences, they typically bind a limited number of ligands. Chemokine receptors are redundant in their function as more than one chemokine is able to bind to a single receptor.
 Links: a. G protein-coupled receptor b. Threonine c. N-terminus d. G protein
Solution:
a